Only a fraction of the earth""s total water supply is available and suitable for agriculture, industry and domestic needs. The demand for water is great and new technologies together with growing populations increase the demand for water while pollution diminishes the limited supply of usable water. The growing demand for water requires efficient use of available water resources.
Agricultural use of water places a large demand on the world""s water supply. In some communities, the water supply may be adequate for farming but the quality of the water is unsuitable for agriculture because the water is alkaline. Alkalinity is an important factor affecting the quality, efficiency and performance of soil and irrigation water. A relative increase in irrigation alkalinity due to the water""s sodium to calcium ratio or a high pH renders irrigation water detrimental to soil, crop growth and irrigation water efficiency. Such water can be reclaimed for soil rehabilitation and irrigation by adding lower pH sulphurous acid to the alkaline water to reduce its alkalinity or pH.
The invention of this application is directed toward a device which generates sulphurous acid in a simplified, efficient way. In particular, it is directed toward a sulphurous acid generator which produces sulphurous acid by burning sulphur to produce sulphur dioxide gas. The sulphur dioxide gas is then drawn toward and held in contact with water eventually reacting with the water and producing sulphurous acid, while substantially reducing dangerous emissions of sulphur dioxide gas to the air.
There are several sulphurous acid generators in the art. The prior art devices utilize sulphur burn chambers and absorption towers. However, known systems utilize countercurrent current flow or pressurized systems as the principle means to accomplish the generation of sulphurous acid. For example, many devices employ the absorption tower to introduce the majority of the water to the system in countercurrent flow to the flow of sulphur dioxide gas. U.S. Pat. No. 4,526,771 teaches introducing 90% of the system water for the first time in countercurrent flow at the top of the absorption tower. In such devices, the integrity of the absorption towers is vital, and any deficiencies or inefficiencies of the absorption tower lead to diminished reaction and results. Other devices utilize pressurized gas to facilitate flow of gas through the system, see U.S. Pat. No. 3,226,201. Pressurized devices, however, require expensive manufacture to ensure the containment of dangerous sulphur dioxide gas to avoid leakage. Even negative pressure machines have the drawback of requiring a source of energy to power the negative pressure generator such as an exhaust fan. Still other devices rely upon secondary combustion chambers to further oxidize the sulphur, see U.S. Pat. No. 4,526,771. Many sulphurous acid generators emit significant or dangerous levels of unreacted sulphur dioxide gas, a harmful and noxious pollutant, into the surrounding environment.
The present invention is directed to a sulphurous acid generator which can be used to improve alkaline irrigation water by adding the sulphurous acid produced by the generator to alkaline water to reduce the alkalinity and/or pH of the water. In addition to making the water less alkaline, adding sulphurous acid to alkaline water increases the availability of sulphur in the water to act as a nutrient, improves capillary action of the soil, increases cation exchange capacity, and decreases tail water run-off and tillage and fertilizer costs.
In many agricultural settings, complicated farm machinery is not practical because it requires technical training to operate and special skills to service and maintain. For sulphur generators, improved design can reduce costs, simplify operation, service and maintenance and increase efficiency and safety thereby making the machine more practical for agricultural use. The present invention is directed toward a sulphurous acid generator that is simple to produce, operate, service and maintain, and which efficiency produces, contains and reacts sulphur dioxide gas and sulphurous acid without exposing the user or other living things in proximity to the machine to dangerous sulphur dioxide emissions.
It will be appreciated that a specific energy source is not necessarily required by the present invention, and therefore its use is not necessarily restricted to locations where a particular power source, like electricity, is available or can be generated for use. All of the above objectives are met by the present invention.
Unlike the prior art, the present invention is designed to maximize the amount of water in contact with sulphur dioxide gas and the duration of the contact of water with sulphur dioxide gas without creating or minimizing back pressure in the system or relying upon pressurization of the gas to cause the sulphur dioxide gas to flow through the sulphurous acid generator. This reduces the complexity of the sulphurous acid generator and the need for additional equipment such as air compressors used by prior art devices.
The invention primarily relates to a sulphur hopper, a burn chamber, a gas pipeline, a mixing tank, an exhaust pipeline, and an exhaust scrubbing tower.
The sulphur hopper preferably has a capacity of several hundred pounds of sulphur in powder, flake, split-pea or pastile form. The sulphur hopper can be constructed of various materials or combinations thereof. In one embodiment, the sulphur hopper is constructed of stainless steel and plastic. In the preferred embodiment the hopper is constructed of Saggregate(trademark) concrete. The sulphur hopper is connected to the burn chamber by a passageway positioned at the base of the sulphur hopper. The conduit joins the burn chamber at its base. The weight of the sulphur in the sulphur hopper forces sulphur through the passageway at the base and into the burn chamber, providing a continual supply of sulphur for burning.
A cooling ring is disposed at the base of the hopper. The cooling ring enters the base of the hopper, traverses a unshaped pattern near the passageway into the burn chamber protruding above the base of the hopper. The cooling ring creates a physical and temperature barrier preventing molten sulphur from flowing across the entire base of the hopper.
The burn chamber has an ignition inlet on the top of the burn chamber through which the sulphur is ignited and an air inlet on the side of the chamber through which oxygen enters to fuel the burning sulphur. The burning sulphur generates sulphur dioxide gas. In the preferred embodiment, the top of the chamber is removable, facilitating access to the chamber for maintenance and service. The burn chamber is constructed of material capable of withstanding the corrosiveness of the sulphur and the heat of combustion, namely stainless steel but preferably Saggregate(trademark) concrete. Saggregate(trademark) concrete is preferred because it significantly decreases the cost of the hopper and burning chamber. Saggregate(trademark) concrete is a unique blend of cement and aggregates.
Sulphur dioxide gas exits the burn chamber through an exhaust outlet on the top of the burn chamber and is drawn into a first conduit. The first conduit may be manufactured from stainless steel.
A supply of water is conducted by a second conduit and may be brought from a water source through the second conduit by any means capable of delivering sufficient water and pressure, such as an elevated water tank or a mechanical or electric pump.
The first conduit and second conduit meet and couple with a third conduit. The third conduit may comprise a blending portion, a contact containment portion, an agitation portion and a means for discharging the sulphurous acid and unreacted sulphur dioxide gas. In the third conduit, the sulphur dioxide gas and water are brought in contact with each other to form sulphurous acid. The third conduit may be constructed of polyethylene plastic, pvc or any durable plastic.
The blending portion of the third conduit comprises a means for bringing the sulphur dioxide gas in the first conduit and the water in the second conduit into contained, codirectional flow into contact with each other. The majority of water used to create sulphurous acid in the system and method is introduced into the third conduit and flows through one or more mixing portions in the third conduit, thereafter discharging naturally by gravity into a mixing tank.
Water is introduced into the third conduit in codirectional flow with the sulphur dioxide gas so as to create an annular column of water with the sulphur dioxide gas flowing inside the annular column of water thereby blending the water and sulphur dioxide gas together. In the preferred embodiment, water is introduced into the gas pipeline and passes through an eductor or venturi, which causes sulphur dioxide gas to be drawn through the first conduit without the need of pressuring the sulphur dioxide gas and without using an exhaust fan. The water and sulphur dioxide gas remain in contact with each other for the period of time it takes to flow through a portion of the third conduit. In the contact area, a portion of the sulphur dioxide gas reacts with the water, creating sulphurous acid.
In different embodiments, an agitation portion comprises a means for mixing and agitating the codirectionally flowing sulphur dioxide gas and water/sulphurous acid. The agitation portions enhance sulphur dioxide gas reaction and dispersion. Bends in or a length of the third conduit or obstructions within the third conduit are contemplated as means for mixing and agitating in the agitation portion. Agitation of the codirectional flow of the sulphur dioxide gas and water further facilitates reaction of the sulphur dioxide gas with water. Sulphurous acid and sulphur dioxide gas flow out of the third conduit through means for discharging the sulphurous acid and unreacted sulphur dioxide gas.
A discharge outlet represents a possible embodiment of means for discharging the sulphurous acid and unreacted sulphur dioxide gas. The discharge outlet permits conduit contents to enter a gas submersion zone.
The sulphurous acid and unreacted sulphur dioxide gas exit the third conduit through the discharge and enter a gas submersion zone or mixing tank. In one embodiment, a weir divides the mixing tank into two sections, namely a pooling section and an effluent or outlet section. Sulphurous acid and sulphur dioxide gas exit the discharge of the third conduit into the pooling section. As the sulphurous acid pours into the mixing tank, it creates a pool of sulphurous acid equal in depth to the height of the weir. At all times, the water/acid and unreacted sulphur dioxide gas discharge from the third conduit above the level of the liquid in the pooling section of the mixing tank. In another embodiment, water/acid and unreacted sulphur dioxide gas discharge from the third conduit to mix in a single cell mixing tank, discharging out the bottom of the mixing tank.
In other words, the discharge from the third conduit is positioned sufficiently high in the mixing tank so that sulphur dioxide gas exiting the pipeline can pass directly into and be submerged within the pool while in an open (nonclosed) arrangement. In other words, the discharge from the third conduit does not create any significant back pressure on the flow of sulphurous acid or sulphur dioxide gas in the third conduit or gas pipeline. Nevertheless, the vertical position of the discharge from the third conduit into the pool reduces the likelihood that the unreacted sulphur dioxide gas will exit from the discharge without being submerged in the pool. In one embodiment, the discharge is removed a distance from the sidewall of the mixing tank toward the center of the pooling section to allow the pool to be efficiently churned by the inflow of sulphurous acid and unreacted sulphur dioxide gas from the third conduit. In another embodiment, discharge out the bottom of the mixing tank upstream from a u-trap efficiently churns unreacted sulphur dioxide gas with the aqueous fluid of the system.
As acidic/water and gas continue to enter the mixing tank from the third conduit in one embodiment, the level of the pool eventually exceeds the height of the weir. Sulphurous acid spills over the weir and into the effluent or outlet section of the mixing tank where the sulphurous acid exits the mixing tank through an effluent outlet. The top of the effluent outlet is positioned below height of the weir and below the discharge from the third conduit in order to reduce the amount of free floating unreacted sulphur dioxide gas exiting the chamber through the effluent outlet. In another embodiment, a discharge in the bottom of a weirless mixing tank employs the column of water to inhibit unreacted sulphur dioxide from exiting the mixing chamber through the bottom discharge outlet. Free floating, unreacted sulphur dioxide gas remaining in the mixing tank rises up to the top of the mixing tank. The top of the mixing tank is adapted with a lid. Undissolved sulphur dioxide gas flowing through the effluent outlet are trapped by a standard u-trap, forcing accumulated gas back into the mixing tank while sulfurous acid exits the system through a first discharge pipe.
To ensure further elimination of any significant emissions of sulphur dioxide gas from the generator into the environment, the sulphur dioxide gas remaining in the mixing tank may be drawn into an exhaust conduit coupled with an exhaust vent on the lid of the mixing tank. The exhaust conduit defines a fourth conduit. Positioned in the fourth conduit is a means for introducing water into the fourth conduit. The water which enters the fourth conduit may be brought from a water source by any means capable of delivering sufficient water to the fourth conduit. As the water is introduced into the fourth conduit, it reacts with the sulphur dioxide gas that has migrated out through the lid of the mixing tank of the absorption tower, and creates sulphurous acid.
In the preferred embodiment, water introduced into the fourth conduit, passes through a second eductor or venturi causing the sulphur dioxide gas to be drawn through the vent and into the fourth conduit. The gas and water are contained in contact as they flow in codirectional flow through one or more contact secondary containment and/or agitation portions of the fourth conduit. Sulphurous acid exits the fourth conduit through a second discharge pipe. The fourth conduit may be constructed of high density polyethylene plastic, pvc or any suitably durable plastic. The material of construction is chosen for its durability and resistance to ultra violet ray degradation. In a preferred embodiment, the second discharge pipe also comprises a u-trap configuration.
In a preferred embodiment upstream from the u-trap of the second discharge pipe, a vent stack houses an exhaust scrubbing tower providing a tertiary containment area. The exhaust scrubbing tower defines grill holes through which the rising, undissolved gases rise. In a preferred embodiment, the exhaust scrubbing tower comprises a cylindrical body which is constructed of polyethylene plastic which is durable, lightweight and resistant to ultra violet ray degradation. At the top of the exhaust scrubbing tower, a third source of water introduces a shower of water through an emitter inside the exhaust tower showering water downward, resulting in a countercurrent flow of undissolved gases and descending water. The rising sulphur dioxide gas comes into countercurrent contact with the descending water, creating sulphurous acid.
The exhaust scrubbing tower is packed with path diverters, which force the countercurrent flow of sulphur dioxide gas and water to pass through a tortuous maze, increasing the duration of time the gas and water remain in contact and the surface area of the contact. Substantially all the free floating sulphur dioxide gas from the mixing tank will react with water in the tower to form sulphurous acid. Sulphurous acid created in the tower flows down into the secondary discharge. Any undissolved gases pass out of the open, upward end of the exhaust scrubbing tower to the atmosphere.
As mentioned, the water introduced into the system to the third conduit, fourth conduit and exhaust scrubbing tower may be brought from a water source to the system by any means capable of delivering sufficient water and pressure, such as a standing, elevated water tank, or mechanical, electric or diesel powered water pump.
The present invention also contemplates means for controlling the burn rate of sulphur in the burning chamber, that is, dampening the flow or amount of air made available into the burning chamber.
It is an object of this invention to create a sulfurous acid generator that is simple to manufacture, use, maintain and service.
It is also an object of this invention to construct the hopper and burn chamber out of a high-temperature concrete to reduce manufacturing costs.
It is another object of this invention to eliminate reliance upon countercurrent absorption as the prior mechanism for creating sulphurous acid as taught by the prior art.
It is further an object of this invention to create a sulfurous acid generator that is capable of operating without any electrical equipment such as pumps, air compressor or exhaust fans requiring a specific energy source requirement, such as electricity or diesel fuels.
It is another object of this invention to produce a sulphurous acid generator which converts substantially all sulfur dioxide gas generated into sulphurous acid.
It is another object of the invention to produce a sulfurous acid generator which uses an induced draw created by the flow of water through the system to draw gases through the otherwise open system.
Another object of the present invention is to provide a sulphurous acid generator with one or more contact containment and/or agitation and mixing mechanisms to increase the duration of time during which the sulphur dioxide gas is in contact with and mixed with water.
It is an object of this invention to produce a sulphurous acid generator which substantially eliminates emission of harmful sulphur dioxide gas.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.